A Facile Approach for Enhanced Keratin Extraction from Tannery Hair Waste Using Crude Protease Enzyme and Optimization of Hydrolysis Parameters by Response Surface Methodology

Abstract

Hair waste in tanneries poses significant environmental and health concerns, which can be mitigated by extracting keratin, which is the major constituent of the hair. In this study, crude protease enzyme was used to extract keratin from sheep hair waste in an eco-friendly manner. The bacterial strain for enzyme preparation was isolated from the soil of a waste dumping site. A mild NaOH (0.2 M) solution was used to break down the disulfide bond of protein which followed the enzymatic hydrolysis process to extract keratin. Several reaction parameters (time, temperature, and pH) of the extraction process were optimized using response surface methodology (RSM). The extensive analysis of data by RSM revealed a hydrolysis time of 5.54 h, a temperature of 54.90 °C, and a pH of 7.87 to be optimum for achieving a maximum keratin yield of 45.43%. Under optimal conditions, laboratory tests produced a keratin yield of 44.77% with a 1.48% error. This approach significantly reduces chemical use and process duration while maintaining higher yields compared to conventional methods. Protein content analysis using the Bradford method and Kjeldahl method showed that the method recovers 84.49% and 94.82% of the protein from the hair waste, respectively. Cost analysis demonstrated that only $19 is needed to obtain 100 g of keratin from tannery hair waste, confirming its economic feasibility. Cytotoxicity assays affirmed the potential applications of extracted keratin in cosmetics, tissue engineering, and biomedical fields. This green approach enables the valorization of sheep hair waste in an eco-friendly, cost-effective, and sustainable manner.